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I got the CH4D neck sizing insert die and squeeze the .303 British necks down to hold a .304 180 gr. Hawk Bullet. I used beginning load data for a 180 Gr. Sierra bullet and loaded 3 rounds.

Went out to the range this afternoon and fired the three rounds.

No problem. No pierced primer, no head separation. Brass fired, extracted and eject easily.



When I got home I tried to insert a .311 bullet into the fired case necks and it would not go.

Now to build some loads for the this gun.

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Wow!
Those ordinary .303 British 174gn FMJ must have had a long ogive, enough to just chamber DD.
They must have raised the pressure quite substantially to say the least!
For some reason I just can't grasp why the first cases almost separated; these last lot don't appear to have protruding primers or show excessive headspace.........what am I missing here?
Great to see that you have it going mate, no wonder you were chaffing at the bit!

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Sounds good. How did they shoot or were you just checking function?

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Checking function, I guess you would say. Just aimed towards the gong and fire. Didn't hear any clangs, but deaf ears without hearing aids and wearing ear protection I couldn't hear church bells while standing in the belfry.

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It would be interesting to see a chamber cast, but in lieu of that, what was the o.d. of the necks and what size slug would fit in the necks of the first fired cases?

I have had fired cases that wouldn't fit the bullet that they fired, but that was due to the pressure of the load and the neck didn't fully expand.

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Pressure is a factor in this case but due to over size bullets in small bore. Check this spread sheet.

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Was the length of the case over on the Remington cases(not that you can tell at this point)? Could the case have pushed into the throat compounding the bore issue and spiking pressure?

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There is no evidence this a factor. One thing I have noticed is the the factory .303 British cartridge will not fully chamber when dropped in the chamber. A light push and the cartridge clicks in to the chamber.

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All of that aside, beautiful rifle and I am also curious about your range report with the Hawk slugs.
Good shooting.

Tom

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The only purpose of the Hawk bullet at this point was to fit the groove diameter. Now that the seems to have worked-load developing time.

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I see a primer protruding .010" or so. Generally means pressure under 35,00psi (or CUP?) Just an observation.
I am assuming a .304" Hawke bullet would fit back into the fired cases.

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Optical illusion no protrusion of primers in the .304 bullet test loads. Tested just too be sure with straight edge.


Here is a comparison of the .303 British factory loads, back row and .304 test loads from.



That back row shows classic pressure signs. Protruding primer, flatten primer, punctured primer and separation of head.

Protruding primercan indicate high pressure on the low end of the scale or excessive headspace. Protruding primers do not alway mean pressure Protruding primer do not always mean headspace. They are just indicators that must be considered in the entire package.

Look at the spread sheet above and see head expansion.

Primer can protrude at any pressure, but what I think you mean is flattening, I have never seen a pressure designation associated with flattening, just that it is usually associated with higher pressures.

Front row, primers are still rounded. No pressure signs.

I have one additional test I am going to do. The factory ammo I used was RP 180 gr. Core-lokt .303 British using .311 bullets.

I have one round of that ammo left. I am going to pull the 180 gr. 311 bullet and replace it with the .304 180 gr. Hawk bullet

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